Little fix for newint.to_bytes()

Author: edschofield

future/types/newint.py

@@ -305,7 +305,7 @@ def to_bytes(self, length, byteorder='big', signed=False):
         if length < 0:
             raise ValueError("length argument must be non-negative")
         if length == 0 and num == 0:
-            return bytes()
+            return newbytes()
         h = b'%x' % num
         s = newbytes((b'0'*(len(h) % 2) + h).zfill(length*2).decode('hex'))
         if len(s) > length: